Variable-period generalized double-vector model predictive current control method and related device

Abstract

The application provides a variable-period generalized double-vector model predictive current control method and related equipment, which comprises the following steps: determining a reference current vector in a synchronous coordinate system according to a q-axis current reference value output by a speed outer loop PI regulator and a given d-axis current reference value; performing one-beat delay compensation to determine a current at k+1 moment; determining a first voltage vector and a second voltage vector acting on the current in a control period from k+1 moment to k+2 moment, and determining a current change rate; determining a first current and a second current in the control period from k+1 moment to k+2 moment; constructing a value function according to the first current, the second current and the reference current vector; determining an action time feasible region of the first voltage vector and the second voltage vector, and determining a target first voltage vector, a target second voltage vector and a target action time with the minimum current harmonic according to the action time feasible region and the value function; and establishing a driving signal of an inverter to control the operation of a permanent magnet synchronous motor.

Description

Technical Field

[0001] This application relates to the field of power control technology, and in particular to a variable-period generalized dual-vector model predictive current control method and related equipment. Background Technology

[0002] In recent years, model predictive control (MMC) has been widely applied in the control of permanent magnet synchronous motors (PMSMs). However, traditional MMC cannot accurately track reference values ​​and exhibits poor steady-state performance. The switching states of an inverter are affected by the voltage vector and its duration. In traditional MMC, the selected voltage vector acts throughout the entire control cycle; that is, the voltage vector's duration is fixed, and the only degree of freedom is the selection of the voltage vector. Limited by the finite number of switching states, traditional MMC cannot accurately track reference values. While steady-state performance can be improved by increasing the switching frequency or reducing the control cycle, this leads to increased switching losses.

[0003] Therefore, it is necessary to explore a method that can improve the steady-state performance of the system without increasing the switching frequency and is easy to implement. Summary of the Invention

[0004] In view of this, the purpose of this application is to propose a variable-period generalized dual-vector model predictive current control method and related equipment to overcome or at least partially solve the above problems.

[0005] To achieve the above objectives, a first aspect of this application provides a variable-period generalized dual-vector model predictive current control method, comprising:

[0006] Based on the q-axis current reference value output by the speed outer loop PI regulator and the given d-axis current reference value, determine the reference current vector in the synchronous coordinate system;

[0007] Obtain the current at time k and perform one-time delay compensation to determine the current at time k+1;

[0008] Determine the first voltage vector and the second voltage vector acting on the current during the control period from time k+1 to time k+2 of the variable-period generalized dual-vector model, and determine the rate of change of the current;

[0009] Based on the first voltage vector, the second voltage vector, and the current change rate, determine the first current and the second current during the control period from time k+1 to time k+2.

[0010] A value function is constructed based on the first current, the second current, and the reference current vector;

[0011] Determine the feasible region of the action time of the first voltage vector and the second voltage vector, and based on the feasible region of the action time and the value function, determine the target first voltage vector, the target second voltage vector and the target action time that minimize the current harmonics;

[0012] Based on the target first voltage vector, the target second voltage vector, and the target action time, a drive signal for the inverter is established to control the operation of the permanent magnet synchronous motor.

[0013] Optionally, the reference current vector is:

[0014]

[0015] in, This is the q-axis current reference value in the synchronous coordinate system. This is the reference value for the d-axis current in the synchronous coordinate system.

[0016] Optionally, the current at time k+1 is expressed as:

[0017]

[0018] in, It is the control period from time k to time k+1; It is the average voltage vector from time k to k+1; ω is the current value at time k; r It is the electric angular velocity; R s L is the stator resistance. s For the quadrature-direct axis inductance, ψ f It is a permanent magnet flux linkage.

[0019] The first current is represented as:

[0020]

[0021] in, Let T1 be the current at time k+1, T1 be the duration of the first voltage vector acting from time k+1 to time k+2, and Δi1 be the rate of change of the current acting on the first voltage vector from time k+1 to time k+2.

[0022] The second current is represented as:

[0023]

[0024] in, Let Δi1 be the current at time k+1, Δi1 be the rate of change of the current at time k+1, T2 be the duration of the second voltage vector acting from time k+1 to time k+2, and Δi2 be the rate of change of the current acting on the second voltage vector from time k+1 to time k+2.

[0025] Optionally, the value function is expressed as:

[0026]

[0027] Where λ is the weighting coefficient; f s Indicates the number of times the switch is turned on and off. The switching state of the second voltage vector from time k to k+1. The switching state of the first voltage vector from time k+1 to k+2. The switching state of the second voltage vector from time k+1 to k+2. As the reference current vector, For the first current, T1 is the duration of the first voltage vector acting from time k+1 to time k+2, and T2 is the duration of the second voltage vector acting from time k+1 to time k+2. This represents the square of the 2-norm.

[0028] Optionally, the feasible domain of the action time is represented as:

[0029] D={T first +T second ≧T min ∩T first +T second ≦T max ∩0≦T first ≦T max ∩0≦T second ≦T max}

[0030] Among them, T max T represents the maximum control period; min T represents the minimum control period. first T is the optimal application time of the first voltage vector acting at time k+1. second The optimal application time for the second voltage vector acting at time k+2;

[0031] The step of determining the feasible region of action time for the first voltage vector and the second voltage vector, and determining the target voltage vector combination and target action time with minimum current harmonics based on the feasible region of action time and the value function, includes:

[0032] Determine the feasible region of action time, and use unconstrained extrema to calculate the optimal action time of the first voltage vector and the second voltage vector in the feasible region;

[0033] If the optimal action time of the first voltage vector and the second voltage vector is not in the feasible region, then the optimal action time of the first voltage vector and the second voltage vector is at the boundary of the feasible region.

[0034] The boundary of the feasible region is solved by using a Lagrangian function to determine the optimal action time of the first voltage vector and the second voltage vector;

[0035] Traverse all voltage vector combinations and solve for the optimal action time of the first and second voltage vectors in all voltage vector combinations;

[0036] Substitute all voltage vector combinations and their optimal action times into the value function, and determine the voltage vector combination with the minimum value function and its optimal action time as the target voltage vector combination and target action time.

[0037] A second aspect of this application provides a variable-period generalized dual-vector model predictive current control device, comprising:

[0038] The current vector module determines the reference current vector in the synchronous coordinate system based on the q-axis current reference value output by the speed outer loop PI regulator and the given d-axis current reference value.

[0039] The compensation module is used to obtain the current at time k and perform a series of delay compensations to determine the current at time k+1.

[0040] The current change rate module is used to determine the first voltage vector and the second voltage vector acting on the current during the control period from time k+1 to time k+2 of the variable period generalized dual vector model, and to determine the current change rate.

[0041] The current determination module is used to determine the first current and the second current during the control period from time k+1 to time k+2 based on the first voltage vector, the second voltage vector and the current change rate.

[0042] The value function module is used to construct a value function based on the first current, the second current, and the reference current vector.

[0043] The target voltage vector determination module is used to determine the feasible region of the action time of the first voltage vector and the second voltage vector, and to determine the target first voltage vector, the target second voltage vector and the target action time with the minimum current harmonics based on the feasible region of the action time and the value function.

[0044] The control module is used to establish the inverter drive signal based on the target first voltage vector, the target second voltage vector and the target action time, so as to control the operation of the permanent magnet synchronous motor.

[0045] A third aspect of this application provides an electronic device including a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that the processor executes the program to implement the method described in the first aspect.

[0046] A fourth aspect of this application provides a non-transitory computer-readable storage medium storing computer instructions, characterized in that the computer instructions are used to cause a computer to perform the method as described in the first aspect.

[0047] As can be seen from the above, the variable-period generalized dual-vector model predictive current control method and related equipment provided in this application add the degree of freedom of variable control period. The action time of each voltage vector can be solved. Taking into account the program execution time and discrete error, and after compensating for the current with a one-beat delay, the feasible region of the action time of the voltage vector combination is defined. The voltage vector combination that minimizes the value function and the optimal action time are determined by solving the value function. Without increasing the switching frequency, the current harmonics are reduced and the steady-state performance of the system is improved.

[0048] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in this application or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the drawings described below are only embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0050] Figure 1 This is a schematic diagram of the variable-period generalized dual-vector model predictive current control method according to an embodiment of this application;

[0051] Figure 2 This is a block diagram of the variable-period generalized two-vector model predictive current control structure according to an embodiment of this application;

[0052] Figure 3 This is a schematic diagram of the feasible time domain for the implementation of an embodiment of this application;

[0053] Figure 4 This is a schematic diagram of the experimental results of predictive current control using a conventional generalized dual vector model in this application, with a switching frequency of 2781Hz and the motor running at 300r / min with rated load.

[0054] Figure 5 This is a schematic diagram of the experimental results of using a variable-period generalized dual-vector model to predict current control in an embodiment of this application, with a switching frequency of 2944Hz and the motor running at 300r / min with rated load.

[0055] Figure 6 This is a schematic diagram of the experimental results of predictive current control using a conventional generalized dual vector model in this application, with a switching frequency of 4890Hz and the motor running at 900r / min with rated load.

[0056] Figure 7 This is a schematic diagram of the experimental results of using variable-period generalized dual-vector model predictive current control in an embodiment of this application, with a switching frequency of 4883Hz and the motor running at 900r / min with rated load.

[0057] Figure 8 This is a schematic diagram of the experimental results of predictive current control using a conventional generalized dual vector model in this application, with a switching frequency of 3763Hz and the motor running at 1500r / min with rated load.

[0058] Figure 9 This is a schematic diagram of the experimental results of using variable-period generalized dual-vector model predictive current control in an embodiment of this application, with a switching frequency of 4000Hz and the motor running at 1500r / min with rated load.

[0059] Figure 10 This is a schematic diagram comparing the switching frequencies of conventional generalized two-vector model predictive current control and variable-period generalized two-vector model predictive current control at different speeds, according to embodiments of this application.

[0060] Figure 11 This is a schematic diagram comparing the current THD of conventional generalized two-vector model predictive current control and variable-period generalized two-vector model predictive current control at different speeds, as shown in the embodiments of this application.

[0061] Figure 12 This is a schematic diagram of a variable-period generalized dual-vector model predictive current control device according to an embodiment of this application;

[0062] Figure 13 This is a speed control system for a permanent magnet synchronous motor according to an embodiment of this application;

[0063] Figure 14 This is a schematic diagram of the hardware structure of an electronic device according to an embodiment of this application. Detailed Implementation

[0064] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with specific embodiments and the accompanying drawings.

[0065] It should be noted that, unless otherwise defined, the technical or scientific terms used in the embodiments of this application should have the ordinary meaning understood by one of ordinary skill in the art to which this application pertains. The terms "first," "second," and similar terms used in the embodiments of this application do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as "comprising" or "including" mean that the element or object preceding the word encompasses the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. Terms such as "upper," "lower," "left," and "right" are only used to indicate relative positional relationships; when the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0066] In related technologies, one method to reduce current harmonics and improve system steady-state operation is to extend the inverter's switching states. Some methods introduce the concept of variable sampling time (VST), dividing a control cycle into multiple sub-cycles and predicting each possible switching state and sampling time. Other methods introduce the concept of navigation tracking, first selecting an optimal direction for tracking a reference value, and then calculating the optimal control cycle in that direction. However, this method ignores the role of the zero vector. Simultaneously, related technologies propose dual-vector model predictive control to suppress torque ripple. A second vector is inserted into one control cycle, and based on the deadbeat principle, two voltage vectors and their application times are obtained, eliminating the computational burden of exhaustive search algorithms. Still other methods propose a fast vector selection method based on three-phase duty cycle, elucidating the relationship between deadbeat predictive current control and model predictive current control. However, in the above methods, the total control cycle of the two voltage vectors is fixed. Even if current harmonics can be controlled, the vector switching is complex and difficult to implement.

[0067] Based on this, refer to Figure 1 , Figure 2 This application provides a variable-period generalized two-vector model predictive current control method, including:

[0068] S101. Determine the reference current vector in the synchronous coordinate system based on the q-axis current reference value output by the speed outer loop PI regulator and the given d-axis current reference value.

[0069] In some embodiments, a reference current command is obtained using a speed outer-loop PI regulator, thereby obtaining the q-axis current reference value in the synchronous coordinate system. The q-axis current reference value is specifically expressed as follows:

[0070]

[0071] Where, k p k is the proportional gain of the PI controller. i ω is the integral gain of the PI controller. r It is electric angular velocity.

[0072] Given d-axis current reference value The value is 0, resulting in the reference current vector. in, This is the q-axis current reference value in the synchronous coordinate system. is the reference value of the d-axis current in the synchronous coordinate system; j is the imaginary unit.

[0073] S102. Obtain the current at time k and perform one-beat delay compensation to determine the current at time k+1.

[0074] In step S102, considering the one-beat delay between the input and output voltages in the digital control system, to eliminate the impact of this delay, the current value at time k is compensated as needed. Based on the mathematical model of the permanent magnet synchronous motor and the current value at time k, one-beat delay compensation is performed to obtain the current at time k+1. Specifically, this is expressed as follows:

[0075]

[0076] in, It is the control period from time k to time k+1; It is the average voltage vector from time k to k+1; ω is the current value at time k; r It is the electric angular velocity; R s L is the stator resistance. s For the quadrature-direct axis inductance, ψ f It is a permanent magnet flux linkage.

[0077] S103. Determine the first voltage vector and the second voltage vector acting on the current during the control period from time k+1 to time k+2, and determine the rate of change of the current.

[0078] Within a control cycle, there may be more than one corresponding first voltage vector and second voltage vector. A voltage vector table is pre-constructed to store all corresponding first and second voltage vectors within the control cycle. It is understood that corresponding first and second voltage vectors can be combined as a single voltage vector.

[0079] Based on the current at time k+1 determined in step S102, the current at future times is predicted. First, the first voltage vector of any voltage vector combination is determined as u. first The second voltage vector is u second The rate of change of current is determined, specifically expressed as:

[0080]

[0081] in, and These represent the first and second voltage vectors acting at times k+1 to k+2, respectively; ω r R is the electric angular velocity; s L is the stator resistance. s For the quadrature-direct axis inductance, ψ f For permanent magnet flux linkage; Let be the current at time k+1.

[0082] S104. Based on the first voltage vector, the second voltage vector, and the rate of change of current, determine the first current and the second current during the control period from time k+1 to time k+2.

[0083] In some embodiments, the rate of change of current from time k+1 to time k+2 is obtained through step S103, and the first current and the second current from time k+1 to time k+2 are determined using the rate of change of current. The first current is specifically expressed as follows:

[0084]

[0085] in, Let be the current at time k+1, T1 be the duration of the first voltage vector acting from time k+1 to time k+2, and Δi1 be the rate of change of the current acting on the first voltage vector from time k+1 to time k+2.

[0086] The second current is specifically represented as follows:

[0087]

[0088] in, Let Δi1 be the current at time k+1, Δi1 be the rate of change of the current at time k+1, T2 be the duration of the second voltage vector acting from time k+1 to time k+2, and Δi2 be the rate of change of the current acting on the second voltage vector from time k+1 to time k+2.

[0089] S105. Construct a value function based on the first current, the second current, and the reference current vector.

[0090] The value function is constructed by taking into account the first current error after the first voltage vector is applied and the second current error after the second voltage vector is applied.

[0091] The value function is specifically expressed as:

[0092]

[0093] Where λ is the weighting coefficient;

[0094] f s Indicates the number of times the switch is turned on and off. The switching state of the second voltage vector from time k to k+1;

[0095] The switching state of the first voltage vector from time k+1 to k+2;

[0096] The switching state of the second voltage vector from time k+1 to k+2;

[0097] The reference current vector;

[0098] This is the first current;

[0099] For the second current;

[0100] T1 is the duration of the first voltage vector acting from time k+1 to time k+2;

[0101] T2 is the duration of the second voltage vector acting from time k+1 to time k+2.

[0102] Based on the principle of minimizing the value function, the optimal first and second voltage vectors and their optimal application time can be determined by finding the minimum value of the value function. It can be understood that the control period T... s k c It's not fixed; the action times of the first and second voltage vectors, as well as the total control cycle, in each voltage vector combination are solved online based on the objective function. Considering that in practical control, the program requires a certain execution time, and that a too-low sampling rate will lead to degraded control performance, a sufficient sampling rate needs to be determined to find the minimum value of the value function over a wider range.

[0103] S106. Determine the feasible region of the action time of the first voltage vector and the second voltage vector. Based on the feasible region and the value function, determine the target voltage vector combination and target action time that minimizes current harmonics.

[0104] In some embodiments, reference Figure 3 As shown, the feasible region is represented as:

[0105] D={T first +T second ≧T min ∩T first +T second ≦T max ∩0≦T first ≦T max ∩0≦T second ≦T max}

[0106] Among them, T max Indicates the maximum control period;

[0107] T min Indicates the minimum control period;

[0108] T first The optimal application time for the first voltage vector acting at time k+1;

[0109] T second The optimal application time for the second voltage vector acting at time k+2.

[0110] Specifically, step S106 includes:

[0111] Determine the feasible region, and use unconstrained extrema to calculate the optimal action time of the first and second voltage vectors in the feasible region.

[0112] If the optimal action time of the first voltage vector and the second voltage vector is not in the feasible region, then the optimal action time of the first voltage vector and the second voltage vector is at the boundary of the feasible region.

[0113] The boundary of the feasible region is solved by using a Lagrangian function to determine the optimal application time of the first voltage vector and the second voltage vector.

[0114] By iterating through all voltage vector combinations, we can determine the optimal action time of the first and second voltage vectors for all voltage vector combinations.

[0115] Substitute all voltage vector combinations and their optimal action times into the value function, and determine the voltage vector combination with the minimum value function and its optimal action time as the target voltage vector combination and target action time.

[0116] The most direct way to determine the feasible region of action time is to find the minimum value of the value function and its corresponding optimal action time within the feasible region. However, this embodiment focuses more on the accurate tracking of the current reference value, and solving for the optimal action time of the first and second voltage vectors with the switching frequency term is very difficult; therefore, the switching frequency term is ignored.

[0117]

[0118] A minimum value over a feasible region can be equivalent to the minimum of an unconstrained extremum and a conditional extremum on the boundary.

[0119] First, regarding the first voltage vector at time k+1... Second voltage vector The optimal action time is determined by using unconstrained extrema.

[0120] Specifically, it is expressed as follows:

[0121]

[0122] However, the solution with the optimal action time may not be within the feasible region of action time.

[0123] If it is determined that the optimal action time is not in the feasible region of action time, then the optimal action time must be located on the boundary of the feasible region of action time. Therefore, it is necessary to construct a Lagrange function.

[0124] The Lagrange function is expressed as:

[0125] h lagrange =h+μD line

[0126] Among them, D line denoted as the boundary of the feasible region of action time; μ is the condition coefficient.

[0127] By finding the extrema of the Lagrange function, the optimal application times of the first and second voltage vectors at time k+1 on the feasible time domain are obtained. Then, the obtained optimal application times are substituted into the value function to obtain the value function value.

[0128] By iterating through all the first and second voltage vectors, the optimal action time for all the first and second voltage vectors is determined using the Lagrange function.

[0129] In some embodiments, for a two-level inverter, all voltage vector combinations include 64 groups. To reduce the computational burden, this application embodiment limits the number of switching operations in one control cycle to no more than once, i.e. Voltage vector groups are stored in a voltage vector table, as shown in Table 1 below.

[0130]

[0131]

[0132] Table 1

[0133] The first and second voltage vectors with the minimum value of the value function and their optimal action time are calculated and used as the target first voltage vector, target second voltage vector, and target action time.

[0134] S107. Based on the first target voltage vector, the second target voltage vector, and the target action time, establish the inverter drive signal to control the operation of the permanent magnet synchronous motor.

[0135] Specifically, the three-phase duty cycle d is calculated using the first target voltage vector, the second target voltage vector, and the target action time. a,b,c and control period T opt Establish the drive signal for the inverter.

[0136] Assumption Control period T opt =T first +T second Three-phase duty cycle:

[0137]

[0138] Therefore, the drive signal for the upper arm switch of phase a is all 1s; the drive signal for the upper arm switch of phase b is 0 to T. first =0, T first ~T opt The value is 1; the drive signal for the upper bridge arm switch of phase c is all zero. The corresponding signal for the lower bridge arm is inverted.

[0139] In some embodiments, the effectiveness of the variable-period generalized two-vector model predictive current control method proposed in this application can be demonstrated by comparison. Figures 4 to 9 Three sets of steady-state simulation results, Figure 10 Comparison of switching frequencies Figure 11 Comparison of current harmonics (THD) and Figure 12 , Figure 13 The results were obtained by comparing the simulation results of forward and reverse rotation. In the simulation, λ = 5 × 10⁻⁶. -7 T sc =100μs, minimum control period T min =0.5T sc =50μs, the maximum value of the control period T max =T sc =100μs, let T be the total duration of action of the phase a current, the first voltage vector, and the second voltage vector. opt =T first +T second In the waveform diagram, from top to bottom, the values ​​represent the motor's mechanical speed, q-axis current, a-phase current, and the total duration T of the first and second voltage vectors. opt With a fixed action time T sc The ratio of is denoted as

[0140] Figure 4 , 5 The waveform is the steady-state waveform under rated load at 300 r / min. The switching frequency of the variable-period generalized two-vector model predictive current control is 2781 Hz. For ease of comparison, the switching frequency of the traditional generalized two-vector model predictive current control should not be lower than that of the variable-period generalized two-vector model predictive current control. Therefore, at 300 r / min, the sampling frequency of the traditional generalized two-vector model predictive current control is set to 7 kHz, and the switching frequency is 2944 Hz. Compared to traditional generalized two-vector model predictive current control, the current THD of variable-cycle generalized two-vector model predictive current control is reduced from 2.60% to 2.26%, a decrease of 13%. Clearly, under the condition of 300 r / min with rated load, variable-cycle generalized two-vector model predictive current control achieves better steady-state performance with a lower switching frequency.

[0141] Figure 6 , 7 The steady-state waveform is given at 900 r / min with rated load. The sampling frequency for the traditional generalized two-vector model predictive current control is set to 11.5 kHz. This ensures that its switching frequency of 4890Hz is greater than the switching frequency of 4883Hz for the variable-period generalized two-vector model predictive current control. Although in Figure 7 middle But T opt The optimal value is obtained based on the principle of minimizing the value function under variable period, and it is fixed at 0.5T. sc This is because the theoretically optimal value is less than 0.5T. sc However, considering the feasible time domain D, it is limited to T. min That is, 0.5T sc The current THD of the traditional generalized two-vector model predicting current control and the variable-period generalized two-vector model predicting current control are 3.55% and 2.34%, respectively, showing a 34% reduction in current THD.

[0142] Figure 8 , 9 The waveform is the steady-state waveform under rated load at 1500 r / min. The switching frequency of the variable-period generalized two-vector model predictive current control is 3763 Hz; the sampling frequency of the traditional generalized two-vector model predictive current control is 12 kHz, and the switching frequency is 4000 Hz. Both methods maintained stable system operation. The variable-period generalized two-vector model predicts current control T... opt Almost all of them are 0.5T sc and T scThis means that the optimal action time lies on the boundary of the feasible region D. The THD of the traditional generalized two-vector model predictive current control and the variable-period generalized two-vector model predictive current control are 2.99% and 2.20%, respectively, representing a 26% reduction in current THD.

[0143] Figure 10 , 11 This paper compares the switching frequency and current THD of the two methods from low speed to high speed. At electrical angular frequencies of 25Hz (300 r / min), 50Hz (600 r / min), 75Hz (900 r / min), 100Hz (1200 r / min), and 125Hz (1500 r / min), the switching frequency and current THD of the variable-cycle generalized dual-vector model predictive current control are all lower than those of the traditional generalized dual-vector model predictive current control. In summary, the variable-cycle generalized dual-vector model predictive current control achieves lower current THD and better steady-state performance than the traditional generalized dual-vector model predictive current control at lower switching frequencies across different speeds.

[0144] It should be noted that the method in this embodiment can be executed by a single device, such as a computer or server. The method can also be applied in a distributed scenario, where multiple devices cooperate to complete the task. In such a distributed scenario, one of these devices may execute only one or more steps of the method in this embodiment, and the multiple devices will interact with each other to complete the method described.

[0145] It should be noted that the above description describes some embodiments of this application. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be performed in a different order than that shown in the above embodiments and still achieve the desired result. Furthermore, the processes depicted in the drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0146] Based on the same technical concept, and corresponding to any of the above embodiments, this application also provides a variable-period generalized dual-vector model predictive current control device.

[0147] refer to Figure 12 The variable-period generalized two-vector model predictive current control device includes:

[0148] The current vector module is used to determine the reference current vector in the synchronous coordinate system based on the q-axis current reference value output by the speed outer loop PI regulator and the given d-axis current reference value.

[0149] The compensation module is used to obtain the current at time k and perform a series of delay compensations to determine the current at time k+1.

[0150] The current change rate module is used to determine the first voltage vector and the second voltage vector acting on the current during the control cycle from time k+1 to time k+2, and to determine the current change rate.

[0151] The current determination module is used to determine the first current and the second current during the control period from time k+1 to time k+2 based on the first voltage vector, the second voltage vector, and the current change rate.

[0152] The value function module is used to construct a value function based on the first current, the second current, and the reference current vector.

[0153] The target voltage vector determination module is used to determine the feasible region of the action time of the first voltage vector and the second voltage vector, and to determine the target first voltage vector, the target second voltage vector and the target action time with the minimum current harmonics based on the feasible region of the action time and the value function.

[0154] The control module is used to establish the inverter's drive signal based on the target first voltage vector, the target second voltage vector, and the target action time, so as to control the operation of the permanent magnet synchronous motor.

[0155] In some embodiments, the reference current vector is:

[0156]

[0157] in, This is the q-axis current reference value in the synchronous coordinate system. This is the reference value for the d-axis current in the synchronous coordinate system.

[0158] In some embodiments, the current at time k+1 is expressed as:

[0159]

[0160] in, It is the control period from time k to time k+1; It is the average voltage vector from time k to k+1; ω is the current value at time k; r It is the electric angular velocity; R s L is the stator resistance. s For the quadrature-direct axis inductance, ψ f It is a permanent magnet flux linkage.

[0161] In some embodiments, the rate of change of current from time k+1 to time k+2 is expressed as:

[0162]

[0163] in, and These represent the first and second voltage vectors acting at times k+1 to k+2, respectively; ω r R is the electric angular velocity; s L is the stator resistance. s For the quadrature-direct axis inductance, ψ f For permanent magnet flux linkage; Let be the current at time k+1.

[0164] In some embodiments, the first current is represented as:

[0165]

[0166] in, Let T1 be the current at time k+1, T1 be the duration of the first voltage vector acting from time k+1 to time k+2, and Δi1 be the rate of change of the current acting on the first voltage vector from time k+1 to time k+2.

[0167] The second current is represented as:

[0168]

[0169] in, Let Δi1 be the current at time k+1, Δi1 be the rate of change of the current at time k+1, T2 be the duration of the second voltage vector acting from time k+1 to time k+2, and Δi2 be the rate of change of the current acting on the second voltage vector from time k+1 to time k+2.

[0170] In some embodiments, the value function is expressed as:

[0171]

[0172] Where λ is the weighting coefficient; f s Indicates the number of times the switch is turned on and off. The switching state of the second voltage vector from time k to k+1. The switching state of the first voltage vector from time k+1 to k+2. The switching state of the second voltage vector from time k+1 to k+2. As the reference current vector, For the first current, T1 is the duration of the first voltage vector acting from time k+1 to time k+2, and T2 is the duration of the second voltage vector acting from time k+1 to time k+2.

[0173] In some embodiments, the feasible domain of action time is represented as:

[0174] D={T first +T second ≧T min ∩T first +T second ≦T max ∩0≦T first ≦T max ∩0≦T second ≦T max}

[0175] Among them, T max T represents the maximum control period; min T represents the minimum control period. first T is the optimal application time of the first voltage vector acting at time k+1. second The optimal application time for the second voltage vector acting at time k+2;

[0176] The target voltage vector determination module is also used for:

[0177] The step of determining the feasible region of action time for the first voltage vector and the second voltage vector, and determining the target voltage vector combination and target action time with minimum current harmonics based on the feasible region of action time and the value function, includes:

[0178] Determine the feasible region of action time, and use unconstrained extrema to calculate the optimal action time of the first and second voltage vectors in the feasible region;

[0179] If the optimal action time of the first voltage vector and the second voltage vector is not in the feasible region, then the optimal action time of the first voltage vector and the second voltage vector is at the boundary of the feasible region.

[0180] By using the Lagrangian function to solve for the boundary of the feasible region, the optimal action time of the first and second voltage vectors can be determined.

[0181] Traverse all voltage vector combinations and solve for the optimal action time of the first and second voltage vectors in all voltage vector combinations;

[0182] Substitute all voltage vector combinations and their optimal action times into the value function, and determine the voltage vector combination with the minimum value function and its optimal action time as the target voltage vector combination and target action time.

[0183] For ease of description, the above devices are described in terms of function, divided into various modules. Of course, in implementing this application, the functions of each module can be implemented in one or more software and / or hardware.

[0184] The apparatus of the above embodiments is used to implement the corresponding variable-period generalized two-vector model predictive current control method in any of the foregoing embodiments, and has the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0185] refer to Figure 13 This application provides a speed control system for a permanent magnet synchronous motor, comprising: a three-phase voltage source, a three-phase diode rectifier bridge, a DC-side capacitor, an inverter, a permanent magnet synchronous motor, a voltage and current sampling module, a drive module, and a variable-period generalized dual-vector model predictive current control device; the voltage and current sampling module collects the DC-side voltage and the a-phase and b-phase currents of the permanent magnet synchronous motor, and the collected signals from the voltage and current sampling module are fed into the variable-period generalized dual-vector model predictive current control device after passing through a zero-order hold, the variable-period generalized dual-vector model predictive current control device performs the calculation of the variable-period generalized dual-vector model predictive current control method, obtains the target first voltage vector, the target second voltage vector, and the target action time, outputs six switching pulses, and then obtains the drive signals of the six switching transistors of the inverter through the drive module.

[0186] Based on the same technical concept, corresponding to the methods of any of the above embodiments, this application also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the variable-period generalized dual-vector model predictive current control method described in any of the above embodiments.

[0187] Figure 14 This embodiment illustrates a more specific hardware structure of an electronic device, which may include a processor 1010, a memory 1020, an input / output interface 1030, a communication interface 1040, and a bus 1050. The processor 1010, memory 1020, input / output interface 1030, and communication interface 1040 are interconnected internally via the bus 1050.

[0188] The processor 1010 can be implemented using a general-purpose CPU (Central Processing Unit), microprocessor, application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided in the embodiments of this specification.

[0189] The memory 1020 can be implemented in the form of ROM (Read Only Memory), RAM (Random Access Memory), static storage device, dynamic storage device, etc. The memory 1020 can store the operating system and other applications. When the technical solutions provided in the embodiments of this specification are implemented by software or firmware, the relevant program code is stored in the memory 1020 and is called and executed by the processor 1010.

[0190] The input / output interface 1030 is used to connect input / output modules to realize information input and output. Input / output modules can be configured as components within the device (not shown in the figure) or externally connected to the device to provide corresponding functions. Input devices may include keyboards, mice, touchscreens, microphones, various sensors, etc., while output devices may include displays, speakers, vibrators, indicator lights, etc.

[0191] The communication interface 1040 is used to connect a communication module (not shown in the figure) to enable communication between this device and other devices. The communication module can communicate via wired means (such as USB, Ethernet cable, etc.) or wireless means (such as mobile network, WIFI, Bluetooth, etc.).

[0192] Bus 1050 includes a pathway for transmitting information between various components of the device, such as processor 1010, memory 1020, input / output interface 1030, and communication interface 1040.

[0193] It should be noted that although the above-described device only shows the processor 1010, memory 1020, input / output interface 1030, communication interface 1040, and bus 1050, in specific implementations, the device may also include other components necessary for normal operation. Furthermore, those skilled in the art will understand that the above-described device may only include the components necessary for implementing the embodiments of this specification, and not necessarily all the components shown in the figures.

[0194] The electronic devices described above are used to implement the corresponding variable-period generalized two-vector model predictive current control method in any of the foregoing embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0195] Based on the same technical concept, corresponding to the methods of any of the above embodiments, this application also provides a non-transitory computer-readable storage medium storing computer instructions for causing the computer to execute the variable-period generalized dual-vector model predictive current control method as described in any of the above embodiments.

[0196] The computer-readable medium of this embodiment includes permanent and non-permanent, removable and non-removable media, and information storage can be implemented by any method or technology. Information can be computer-readable instructions, data structures, program modules, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transfer medium that can be used to store information accessible by a computing device.

[0197] The computer instructions stored in the storage medium of the above embodiments are used to cause the computer to execute the variable-period generalized dual-vector model predictive current control method as described in any of the above embodiments, and have the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0198] Based on the same inventive concept, corresponding to the variable-period generalized two-vector model predictive current control method described in any of the above embodiments, this disclosure also provides a computer program product, which includes computer program instructions. In some embodiments, the computer program instructions can be executed by one or more processors of a computer to cause the computer and / or the processor to execute the variable-period generalized two-vector model predictive current control method. Corresponding to the execution entity for each step in each embodiment of the variable-period generalized two-vector model predictive current control method, the processor executing the corresponding step can belong to the corresponding execution entity.

[0199] The computer program product of the above embodiments is used to enable the computer and / or the processor to execute the variable-period generalized dual-vector model predictive current control method as described in any of the above embodiments, and has the beneficial effects of the corresponding method embodiments, which will not be repeated here.

[0200] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this application (including the claims) is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of the embodiments of this application as described above, which are not provided in the details for the sake of brevity.

[0201] Additionally, to simplify the description and discussion, and to avoid obscuring the embodiments of this application, the well-known power / ground connections to integrated circuit (IC) chips and other components may or may not be shown in the provided drawings. Furthermore, the apparatus may be shown in block diagram form to avoid obscuring the embodiments of this application, and this also takes into account the fact that the details of the implementation of these block diagram apparatuses are highly dependent on the platform on which the embodiments of this application will be implemented (i.e., these details should be fully understood by those skilled in the art). While specific details (e.g., circuits) have been set forth to describe exemplary embodiments of this application, it will be apparent to those skilled in the art that the embodiments of this application can be implemented without these specific details or with variations thereof. Therefore, these descriptions should be considered illustrative rather than restrictive.

[0202] Although this application has been described in conjunction with specific embodiments thereof, many substitutions, modifications, and variations of these embodiments will be apparent to those skilled in the art from the foregoing description. For example, other memory architectures (e.g., dynamic RAM (DRAM)) may be used with the embodiments discussed.

[0203] The embodiments of this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the embodiments of this application should be included within the protection scope of this application.

Claims

1. A variable-period generalized two-vector model predictive current control method, characterized in that, include: Based on the q-axis current reference value output by the speed outer loop PI regulator and the given d-axis current reference value, determine the reference current vector in the synchronous coordinate system; Obtain the current at time k and perform one-beat delay compensation to determine the current at time k+1; wherein, the current at time k+1 is expressed as: in, It is the control period from time k to time k+1; It is the average voltage vector from time k to k+1; Let be the current value at time k; It is electric angular velocity; For stator resistance, It is a direct-axis inductor. For permanent magnet flux linkage; Determine the first voltage vector and the second voltage vector acting on the current during the control period from time k+1 to time k+2, and determine the rate of change of the current; wherein, the rate of change of the current from time k+1 to time k+2 is expressed as: in, and These represent the first voltage vector and the second voltage vector acting at times k+1 to k+2, respectively. Electric angular velocity; For stator resistance, It is a direct-axis inductor. For permanent magnet flux linkage; Let be the current at time k+1; Based on the first voltage vector, the second voltage vector, and the current change rate, determine the first current and the second current during the control period from time k+1 to time k+2. A value function is constructed based on the first current, the second current, and the reference current vector; wherein the value function is expressed as: in, These are the weighting coefficients; Indicates the number of times the switch is turned on and off. , The switching state of the second voltage vector from time k to k+1. The switching state of the first voltage vector from time k+1 to k+2. The switching state of the second voltage vector from time k+1 to k+2. As the reference current vector, For the first current, For the second current, The duration of the first voltage vector acting from time k+1 to time k+2. The duration of the second voltage vector acting from time k+1 to time k+2. Represents the square of the 2-norm; The feasible region of the action time for the first voltage vector and the second voltage vector is determined. Based on the feasible region of the action time and the value function, the target first voltage vector, the target second voltage vector, and the target action time for minimizing current harmonics are determined; wherein, the feasible region of the action time is expressed as: in, Indicates the maximum control period; Indicates the minimum control period. The optimal application time for the first voltage vector acting at time k+1. The optimal application time for the second voltage vector acting at time k+2; Based on the target first voltage vector, the target second voltage vector, and the target action time, a drive signal for the inverter is established to control the operation of the permanent magnet synchronous motor.

2. The method according to claim 1, characterized in that, The reference current vector is: in, This is the q-axis current reference value in the synchronous coordinate system. This is the reference value for the d-axis current in the synchronous coordinate system; It is the imaginary unit.

3. The method according to claim 1, characterized in that, The first current is represented as: in, Let be the current at time k+1. The duration of the first voltage vector acting from time k+1 to time k+2. The rate of change of current acting on the first voltage vector from time k+1 to time k+2; The second current is represented as: in, Let be the current at time k+1. Let be the rate of change of current at time k+1. The duration of the second voltage vector acting from time k+1 to time k+2. The rate of change of current applied by the second voltage vector from time k+1 to time k+2.

4. The method according to claim 1, characterized in that, The step of determining the feasible region of action time for the first voltage vector and the second voltage vector, and determining the target voltage vector combination and target action time with minimum current harmonics based on the feasible region of action time and the value function, includes: Determine the feasible region of action time, and use unconstrained extrema to calculate the optimal action time of the first voltage vector and the second voltage vector in the feasible region; If the optimal action time of the first voltage vector and the second voltage vector is not in the feasible region, then the optimal action time of the first voltage vector and the second voltage vector is at the boundary of the feasible region. The boundary of the feasible region is solved by using a Lagrangian function to determine the optimal action time of the first voltage vector and the second voltage vector; Traverse all voltage vector combinations and solve for the optimal action time of the first and second voltage vectors in all voltage vector combinations; Substitute all voltage vector combinations and their optimal action times into the value function, and determine the voltage vector combination with the minimum value function and its optimal action time as the target voltage vector combination and target action time.

5. A variable-period generalized two-vector model predictive current control device, characterized in that, The apparatus performs the method as described in any one of claims 1 to 4, the apparatus comprising: The current vector module is used to determine the reference current vector in the synchronous coordinate system based on the q-axis current reference value output by the speed outer loop PI regulator and the given d-axis current reference value. The compensation module is used to obtain the current at time k and perform a series of delay compensations to determine the current at time k+1. The current change rate module is used to determine the first voltage vector and the second voltage vector acting on the current during the control period from time k+1 to time k+2, and to determine the current change rate. The current determination module is used to determine the first current and the second current during the control period from time k+1 to time k+2 based on the first voltage vector, the second voltage vector and the current change rate. The value function module is used to construct a value function based on the first current, the second current, and the reference current vector. The target voltage vector determination module is used to determine the feasible region of the action time of the first voltage vector and the second voltage vector, and to determine the target first voltage vector, the target second voltage vector and the target action time with the minimum current harmonics based on the feasible region of the action time and the value function. The control module is used to establish the inverter drive signal based on the target first voltage vector, the target second voltage vector and the target action time, so as to control the operation of the permanent magnet synchronous motor.

6. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that, When the processor executes the program, it implements the method as described in any one of claims 1 to 4.

7. A non-transitory computer-readable storage medium storing computer instructions, characterized in that, The computer instructions are used to cause the computer to perform the method as described in any one of claims 1 to 4.

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